JP6262053B2 - Foam sheet laminate, fiber-reinforced composite, and foam sheet laminate manufacturing method - Google Patents

Description

  The present invention relates to a foam sheet laminate, a fiber reinforced composite, and a method for producing a foam sheet laminate.

  The fiber reinforced composite includes a core material and a fiber reinforced synthetic resin body laminated on the surface of the core material, and is lightweight and has high mechanical strength. Since the fiber reinforced composite has such characteristics, it is used in the automobile field, the ship field, the aircraft field, the windmill field, the pressure vessel field, the home appliance field, the medical device field, the robot field, and the like. It is used as a body member for ships, aircrafts, and the like.

In recent years, further weight reduction has been demanded for fiber reinforced composites. Since the foam is lightweight, attempts have been made to use it as a core material of a fiber-reinforced composite.
As the foam, it has been proposed to use a polyester-based resin foam because it has excellent rigidity (for example, Patent Document 1).
It has also been proposed to use a foam sheet laminate in which foam sheets are laminated as a core material.

JP 2014-028920 A

By the way, in recent years, since fiber reinforced composites are required to have even higher bending strength and compressive strength, the core sheet foam sheet laminate is also required to have such characteristics. It has become.
Further, not only the foamed sheet laminate used as the core material of the fiber reinforced composite, but also the foamed sheet laminate used for other applications is desired to have even better bending strength and compressive strength.

  Then, this invention makes it a subject to provide the foamed sheet laminated body and fiber reinforced composite_body | complex which are excellent in bending strength and compressive strength in view of the said request point.

In the present invention, a plurality of foam sheets formed of a thermoplastic polyester resin are laminated and integrated,
A plurality of foam layers formed of the foam sheet are provided,
It exists in the foam sheet laminated body whose average value of the aspect-ratio of the bubble shown to following formula (1) is 0.6-1.2.
Air bubble aspect ratio = bubble diameter in a direction perpendicular to the laminate surface of the foam sheet / bubble diameter in a direction parallel to the laminate surface of the foam sheet (1)

  The present invention also includes a foam sheet laminate as a core material and a fiber reinforced synthetic resin body laminated on the surface of the core material, and the foam sheet laminate is used as the core material. There is a fiber reinforced composite.

Furthermore, the present invention is a method for producing a foam sheet laminate, wherein a plurality of foam sheets are integrated,
A first step of heating a laminated body formed by laminating a plurality of the foamed sheets formed of a thermoplastic polyester-based resin while regulating the laminated body to a thickness equal to or less than a natural state of the laminated body;
After the first step, while heating the laminate, a second step of increasing the thickness of the laminate and increasing the thickness of each of the foam sheets from the thickness before the first step, It exists in the manufacturing method of the foam sheet laminated body provided.

  ADVANTAGE OF THE INVENTION According to this invention, the foam sheet laminated body and fiber reinforced composite which are excellent in bending strength and compressive strength can be provided.

The schematic sectional drawing which shows one state in the process of producing a fiber reinforced composite.

  Hereinafter, an embodiment of the present invention will be described.

The foamed sheet laminate of this embodiment is formed by laminating and integrating a plurality of foamed sheets formed of a thermoplastic polyester resin, and includes a plurality of foamed layers formed of the foamed sheets.
In the foamed sheet laminate of the present embodiment, it is important that the average value of the aspect ratio (Ac) of the bubbles shown in the following formula (1) is 0.6 to 1.2, and 0.7 to 1.1 is preferable.
Air bubble aspect ratio = bubble diameter in a direction perpendicular to the laminated surface of the foamed sheet (vertical diameter) / bubble diameter in a direction parallel to the laminated surface of the foamed sheet (parallel diameter) (1)
When this average value is 0.6 or more, the foamed sheet laminate is excellent in compressive strength and foam strength even when external pressure is applied in a direction perpendicular to the laminated surface, and in bending strength. Will also be excellent.
Moreover, when this average value is 1.2 or less, the foamed sheet laminate exhibits excellent repulsive force during compression, particularly when compressed in a heated state, and has excellent formability. The bending strength is also excellent.

The average value of the bubble aspect ratio is obtained as follows.
That is, first, the foam sheet laminate is cut in a direction perpendicular to the laminate surface of the foam sheet to form a first cut surface, and the first cut surface is photographed at 200 times using a scanning electron microscope, Randomly, 100 bubbles observed in this photograph are selected, the vertical diameter and the parallel diameter of each bubble are obtained, and the ratio of the vertical diameter to the parallel diameter is defined as the aspect ratio of each bubble. Next, the foamed sheet laminate is cut in a direction perpendicular to the laminated surface of the foamed sheet and also perpendicular to the first cut surface to form a second cut surface, and using a scanning electron microscope The first cut surface was photographed at a magnification of 200 times, and 100 bubbles observed in this photograph were randomly selected, the vertical diameter and the parallel diameter of each bubble were obtained, and the ratio of the vertical diameter to the parallel diameter was determined for each individual bubble. The aspect ratio of the bubbles. And the aspect ratio of these bubbles is arithmetically averaged, and this arithmetic average value is taken as the average value of the aspect ratio of the bubbles of the foamed sheet laminate.
In addition, on the outer contour line of the bubble cross section, two points having the maximum mutual distance in the direction perpendicular to the laminated surface are selected, and the distance between the two points is defined as a “vertical diameter”. Further, on the outer contour line of the bubble cross section, two points having the maximum mutual distance in the direction parallel to the laminated surface are selected, and the distance between the two points is defined as the “parallel diameter”.
In addition, bubbles whose outer contour line covers the cross section are excluded from the aspect ratio measurement target. For example, when an unfoamed skin on a plane parallel to the laminating direction is cut and removed from the foamed sheet laminate, there may be a bubble having an outer contour line covering the cross section.

  Furthermore, the average vertical diameter of the bubbles of the foamed sheet laminate of the present embodiment is preferably 0.05 to 0.8 mm, more preferably 0.08 to 0.6 mm, and particularly preferably 0.1 to 0.5 mm. When the average vertical diameter of the bubbles is 0.05 mm or more, the foamed sheet laminate is advantageous in that it is flexible, hardly breaks, and can sufficiently absorb impact energy. When the average vertical diameter of the bubbles is 0.8 mm or less, the foamed sheet laminate has an advantage that the hardness becomes high and sufficient mechanical strength can be obtained.

  In addition, the average vertical diameter of the bubbles contained in the foamed sheet laminate is the same as in the measurement of the aspect ratio of the bubbles. Can be obtained by calculating the arithmetic average value of.

Moreover, the foamed sheet laminate of this embodiment includes at least one non-foamed layer.
As the non-foamed layer, a heat-melted layer obtained by heat-melting the surface portion of the foamed sheet in a non-foamed state, a skin layer of the foamed sheet itself, a non-foamed layer provided on the outermost surface of the foamed sheet laminate A non-foamed resin film layer or a non-foamed resin film layer interposed between the foamed sheets.

As a resin film which comprises the said resin film layer, a synthetic resin film like a thermoplastic resin film or a thermosetting resin film is preferable, and a thermoplastic resin film is more preferable.
The thermoplastic resin is not particularly limited. For example, polyolefin resin such as polypropylene resin and polyethylene resin, polyester resin, polyvinyl chloride resin, acrylic resin, polyurethane resin, fluorine resin, ABS resin. Polyester resins, acrylic resins, and ABS resins are preferable because of excellent heat resistance, moldability, and durability.
The thermosetting resin is not particularly limited, and examples thereof include an epoxy resin, an unsaturated polyester resin, a phenol resin, a melamine resin, a polyurethane resin, a silicon resin, a maleimide resin, a vinyl ester resin, and a cyanate ester resin. From the viewpoint of excellent heat resistance, impact absorption or chemical resistance, epoxy resins and vinyl ester resins are preferred. The thermosetting resin may contain additives such as a curing agent and a curing accelerator. In addition, as a thermosetting resin, 1 type may be used independently or 2 or more types may be used together.

Moreover, the adhesive bond layer may be formed in the single side | surface or both surfaces of the said resin film layer. The adhesive constituting the adhesive layer is not particularly limited. For example, in addition to an acrylic pressure-sensitive adhesive and a rubber-based pressure sensitive adhesive, acrylic, polyurethane, polyolefin, polyester, nylon Hot-melt type adhesives such as a system are mentioned. As the adhesive, an acrylic pressure sensitive adhesive, an acrylic hot melt adhesive, and a polyester hot melt adhesive are preferable from the viewpoint of excellent heat resistance and adhesiveness.
Further, the thickness of the resin film layer (when there are a plurality of resin film layers, the thickness of each layer of the resin film layer) is preferably 5 to 800 μm, and more preferably 10 to 600 μm.
The resin film layer may be a fiber reinforced synthetic resin sheet containing fibers in the resin as described later.

  In the foamed sheet laminate of the present embodiment, the ratio of the total thickness of the foamed layer to the total thickness of the non-foamed layer is preferably 30 to 110, and more preferably 40 to 100. . When the ratio of the total thickness of the foamed layer to the total thickness of the non-foamed layer is 30 or more, the foamed sheet laminate has an advantage of being excellent in lightness. Further, when the ratio of the total thickness of the foamed layer to the total thickness of the non-foamed layer is 110 or less, the foamed sheet laminate can increase the ratio of the non-foamed layer, and the mechanical strength. It has the advantage of being excellent.

  In addition, a foamed layer means the layer by which the cross section of a foamed sheet laminated body is image | photographed 200 times using a scanning electron microscope, and a bubble is observed in this photograph. On the other hand, the non-foamed layer means a layer in which bubbles are not observed in this photograph.

Moreover, it is preferable that an apparent density is 0.40 g / cm < ³ > or less, and, as for the foamed sheet laminated body of this embodiment, it is more preferable that it is 0.30 g / cm < ³ > or less from a lightweight viewpoint. On the other hand, from the viewpoint of excellent mechanical strength, it is preferably 0.08 g / cm ³ or more, and more preferably 0.10 g / cm ³ or more.
The apparent density can be measured according to the method described in JIS K 7222: 2005 “Foamed Plastics and Rubber—How to Obtain Apparent Density”.

The plurality of foamed layers include a minimum density region having the smallest apparent density at the center in the thickness direction of each layer.
In addition, it is confirmed as follows whether the plurality of foamed layers are provided with the minimum density region having the smallest apparent density at the center in the thickness direction of each layer.
That is, first, the plurality of foam layers are sliced in parallel with the thickness direction at intervals of 0.3 mm in the thickness direction (stacking direction). Next, the apparent density of each slice portion is determined by a method similar to the method for determining the apparent density of the foamed sheet laminate described above, and a plurality of the foamed layers have a minimum density area with the smallest apparent density. Check if it is provided in the center of the direction.
In the foam sheet laminate of this embodiment, from the viewpoint of excellent compressive strength, the average value of the aspect ratio of the bubbles in the region with the smallest apparent density among the plurality of the minimum density regions is 1.4 or more. It is preferable that it is 1.5 or more.
The average value of the bubble aspect ratio in the minimum density region is determined as follows.
That is, the average value of the aspect ratios of the bubbles in the region having the smallest apparent density among the plurality of the minimum density regions is obtained by setting the region having the smallest apparent density in each layer of the foam layer as the minimum density region. In addition, the average value of the aspect ratio of the bubbles in the slice portion is obtained by a method similar to the method for obtaining the average value of the aspect ratio of the bubbles of the foamed sheet laminate. That is, the average value of the aspect ratios of the bubbles in the region where the apparent density is the smallest in the cross section of the foamed sheet laminate is obtained. At this time, the vertical diameter and the parallel diameter are measured only for the bubbles in which 50% or more of the cross-sectional area of the bubbles is included in the 0.3 mm range of the portion determined to be the smallest apparent density by the slice. The average value of the aspect ratio is obtained.

Furthermore, in the foam sheet laminate of the present embodiment, from the viewpoint of excellent compressive strength, the average value of the aspect ratio of the bubbles in the minimum density region is preferably 1.3 or more in all the foam layers. 1.4 or more is more preferable.
The average value of the aspect ratio of the bubbles in the minimum density region is the same as the method for obtaining the average value of the aspect ratio of the bubbles in the foamed sheet laminate, as the average value of the aspect ratio of the bubbles in the minimum density region. Seek by how to ask.

Further, in the foamed sheet laminate of the present embodiment, the plurality of foamed layers are provided with a minimum density region having the smallest apparent density at the center in the thickness direction of each layer, and one of the foamed sheets is foamed. The outermost surface of the sheet is provided with a heat-melt layer formed by heat-melting one surface side of the sheet, and the apparent density of the surface layer portion including the heat-melt layer provided on the outermost surface is the most apparent among the plurality of the minimum density regions. It is preferably 1.3 times or more, more preferably 1.4 times or more, with respect to the apparent density of the region where the density is small. By having such a configuration, the foamed sheet laminate of the present embodiment has an advantage that the surface layer portion becomes hard and a high initial load can be expressed in the surface layer portion. In addition, the foamed sheet laminate of this embodiment has such a configuration, so that the force applied locally at the surface layer portion is dispersed in the plane direction, and the dispersed force is absorbed by the entire foamed sheet laminate. And as a result, it has the advantage of being excellent in energy absorption.
The apparent density of the surface layer part and the apparent density of the minimum density region of each foam layer are determined as follows.
That is, the foam layer of the foam sheet laminate is sliced from the surface in parallel with the thickness direction at intervals of 0.3 mm in the thickness direction. Next, the apparent density of the first slice portion that hits the surface layer portion and the apparent density of the slice portion that hits the minimum density region are obtained by the same method of obtaining the apparent density of the foamed sheet laminate described above. Thus, the apparent density of the surface layer part and the apparent density of the minimum density region of each foam layer are obtained.

Moreover, the foamed sheet laminate of the present embodiment includes a thermal melt layer formed by thermally melting one surface side of one of the plurality of foam sheets on the outermost surface, and is provided on the outermost surface. It is preferable that the crystallization heat amount of the surface layer portion including the heat-melted layer is 5.0 mJ / mg or less. Moreover, it is more preferable that this crystallization calorie | heat amount is 3.0 mJ / mg or less.
By having such a configuration, the foamed sheet laminate of the present embodiment has an advantage that the surface layer portion becomes hard and a high initial load can be expressed in the surface layer portion. In addition, the foamed sheet laminate of this embodiment has such a configuration, so that the force applied locally at the surface layer portion is dispersed in the plane direction, and the dispersed force is absorbed by the entire foamed sheet laminate. And as a result, it has the advantage of being excellent in energy absorption.
The amount of crystallization heat in the surface layer portion is determined as follows.
That is, the foam layer of the foam sheet laminate is sliced from the surface in a thickness direction of 0.3 mm in parallel with the thickness direction. Then, the amount of crystallization heat at the first slice portion corresponding to the surface layer portion is measured.
The amount of crystallization heat means a value measured by the method described in JIS K7122: 1987 “Method for measuring the transition heat of plastic”.
Specifically, the crystallization calorific value is measured using a differential scanning calorimeter DSC6220 type (manufactured by SII Nano Technology Co., Ltd.). More specifically, about 6 mg of the sample is filled so that there is no gap in the bottom of the aluminum measurement container, and the sample is set in the differential scanning calorimeter device DSC 6220 (made by SII Nano Technology Co., Ltd.) together with the container. The sample is held for 2 minutes at 30 ° C. under a nitrogen gas flow rate of 20 mL / min. Then, a DSC curve is created when the sample is heated from 30 ° C. to 290 ° C. at a rate of 10 ° C./min. At this time, alumina is used as a reference material.
Then, the amount of crystallization heat (mJ / mg) is determined from the area of the crystallization peak of the DSC curve.

Furthermore, in the foamed sheet laminate of the present embodiment, from the viewpoint of excellent bending strength, “specific bending maximum point stress” obtained by dividing “maximum bending point stress” by “apparent density of foamed sheet laminate” is preferably It is 15 MPa / (g / cm ³ ) or more, more preferably 20 MPa / (g / cm ³ ) or more.
The “specific bending maximum point stress” means that measured by the method described in Examples described later.

In addition, in the foam sheet laminate of the present embodiment, from the viewpoint of excellent compressive strength, "25% deformation compressive stress" obtained by dividing "25% deformation compressive stress" by "apparent density of foam sheet laminate" It is preferably 6.5 MPa / (g / cm ³ ) or more.
In addition, "ratio 25% deformation compressive stress" means what was measured by the method as described in the Example mentioned later.

  Examples of the thermoplastic polyester resin include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polytrimethylene naphthalate, and polyethylene terephthalate is preferable. In addition, a thermoplastic polyester-type resin may be used independently, or 2 or more types may be used together.

The intrinsic viscosity (hereinafter also referred to as “IV value”) of the thermoplastic polyester resin is preferably 0.8 to 1.5, more preferably 1.0 to 1.3.
The IV value is a value measured according to JIS K7367-5: 2000.

Next, the manufacturing method of the foam sheet laminated body of this embodiment is demonstrated.
The manufacturing method of the foam sheet laminated body of this embodiment is a method of integrating a plurality of foam sheets.
Further, the method for producing a foamed sheet laminate of the present embodiment regulates a laminate formed by laminating a plurality of the foamed sheets formed of a thermoplastic polyester resin to a thickness equal to or less than a thickness of the laminate in a natural state. The first step of heating while, and after the first step, the thickness of the laminate is increased while heating the laminate, and the thickness of each of the foam sheets is greater than the thickness before the first step. And a second step of increasing.

In the method for producing the foamed sheet, a foamable resin composition is obtained by supplying a thermoplastic polyester resin, a foaming agent, a cell regulator and a crosslinking agent to an extruder and melt-kneading.
And a foaming resin composition is extruded from the circular die | dye attached to the front-end | tip of an extruder, and a cylindrical foamed sheet is formed.
Next, the foamed sheet is drawn while the inner surface of the foamed sheet is slidably contacted with the outer peripheral surface of the cooling mandrel disposed downstream (forward in the extrusion direction) of the circular die, and the foamed sheet is expanded by the cooling mandrel. At the same time, the foam sheet is cooled by a mandrel from the inside of the foam sheet, air is blown from the outside of the foam sheet to cool the foam sheet, and the foam sheet is extruded by a cutter provided on the downstream side of the cooling mandrel. Continuously cut in the direction and developed so as to form a flat sheet, to produce a long strip foam sheet.

Examples of the blowing agent include saturated aliphatic hydrocarbons, halogenated hydrocarbons, carbon dioxide and nitrogen.
Examples of the saturated aliphatic hydrocarbon include propane, butane, pentane and the like. Examples of the halogenated hydrocarbon include tetrafluoroethane, chlorodifluoroethane, and difluoroethane.
As for the usage-amount of the said foaming agent, 0.1-10 mass parts is preferable with respect to 100 mass parts of thermoplastic polyester-type resin.

Examples of the bubble adjusting agent include inorganic nucleating agents and organic nucleating agents.
Examples of the inorganic nucleating agent include talc and silica. Examples of the organic nucleating agent include polytetrafluoroethylene.
As for the usage-amount of the said bubble regulator, 0.1-5 mass parts is preferable with respect to 100 mass parts of thermoplastic polyester-type resins.

Examples of the crosslinking agent include acid dianhydrides such as pyromellitic anhydride, polyfunctional epoxy compounds, oxazoline compounds, and oxazine compounds. In addition, a crosslinking agent may be used independently or 2 or more types may be used together.
As for the usage-amount of the said crosslinking agent, 0.05-2 mass parts is preferable with respect to 100 mass parts of thermoplastic polyester-type resins.

In the first step, in a heating press provided with two hot plates, a laminate in which a plurality of foam sheets are laminated is sandwiched between two heated hot plates. And it heats, controlling a laminated body below to the thickness in the natural state of a laminated body by pressurizing a laminated body with a hot platen.
The laminate may have at least one of a non-foamed resin film layer provided on the outermost surface and a non-foamed resin film layer interposed between the foamed sheets. Good.

  In the second step, after the first step, the distance between the hot plates is gradually increased while the laminate is heated by the heat of the hot plate and the laminate is held between two hot plates. The thickness of the laminate is increased so that the thickness of each of the foamed sheets is larger than the thickness before the first step.

  In the method for producing a foamed sheet laminate of the present embodiment, after the second step, the foamed sheets are heated and fused together by further heating the laminate with the heat of the hot plate. And the foamed sheet laminated body is obtained by water-cooling the inside of the hotplate of a heating press machine.

  The manufacturing method of the foamed sheet laminate of the present embodiment can increase the aspect ratio of the bubbles of the foamed sheet by performing the first step and the second step, and as a result, the foamed sheet laminate obtained as a result. Has an advantage that it has excellent compressive strength.

  Moreover, since the manufacturing method of the foamed sheet laminated body of this embodiment becomes easy to apply especially heat to the surface part of the foamed sheet laminated body obtained by heating from both sides of the laminated foamed sheet, the foamed sheet laminated body This has the advantage that the surface layer portion becomes hard and the foamed sheet laminate is excellent in bending strength.

Next, the fiber reinforced composite of this embodiment will be described.
The fiber reinforced composite of this embodiment includes a foam sheet laminate as a core material and a fiber reinforced synthetic resin body laminated on the surface of the core material, and the foam sheet laminate of this embodiment is used as the core material. The body is used.
In the fiber-reinforced composite of this embodiment, the average aspect ratio of the bubbles is preferably 0.6 to 1.2. In addition, if the average value of the aspect ratio of the bubbles in the foam sheet laminate before being laminated to the fiber reinforced synthetic resin body is 0.6 to 1.2, the aspect ratio of the bubbles in the fiber reinforced composite of the present embodiment The average value of may be less than 0.6 and may exceed 1.2.

Examples of reinforcing fibers of the fiber-reinforced synthetic resin body include inorganic fibers such as glass fibers, carbon fibers, silicon carbide fibers, alumina fibers, tyrano fibers, basalt fibers, and ceramic fibers; metal fibers such as stainless fibers and steel fibers; aramid fibers Organic fibers such as polyethylene fiber and polyparaphenylene benzoxador (PBO) fiber; boron fiber and the like. Reinforcing fibers may be used alone or in combination of two or more. Among these, carbon fiber, glass fiber, and aramid fiber are preferable and carbon fiber is more preferable from the viewpoint of having excellent mechanical properties despite being lightweight.
The reinforcing fiber is preferably used as a reinforcing fiber substrate processed into a desired shape. Examples of the reinforcing fiber base material include a face material obtained by binding (stitching) a fiber bundle (strand) with a thread. The fiber bundle is a woven fabric, knitted fabric, non-woven fabric, and reinforcing fiber that are reinforced fibers are aligned in one direction. Examples of the weaving method include plain weave, twill weave and satin weave. Examples of the yarn include resin yarn such as polyamide resin yarn and polyester resin yarn, and stitch yarn such as glass fiber yarn.
About the said fiber reinforced synthetic resin body, you may use without laminating | stacking only one fiber reinforced synthetic resin sheet, and may laminate | stack and use a plurality of fiber reinforced synthetic resin sheets. As a fiber reinforced synthetic resin body in which a plurality of fiber reinforced synthetic resin sheets are laminated, (1) a fiber reinforced synthetic resin in which only one kind of fiber reinforced synthetic resin sheet is prepared and these fiber reinforced synthetic resin sheets are laminated. Body, (2) a fiber reinforced synthetic resin body in which a plurality of types of fiber reinforced synthetic resin sheets are prepared and these fiber reinforced synthetic resin sheets are laminated, and (3) a fiber bundle (strand) in which the reinforced fibers are aligned in one direction A plurality of fiber reinforced synthetic resin sheets obtained by binding (sewing) with a yarn are prepared, and these fiber reinforced synthetic resin sheets are overlapped so that the fiber directions of the fiber bundles are different from each other. A fiber reinforced synthetic resin body formed by integrating (stitching) fiber reinforced synthetic resin sheets with a thread is used. Examples of the yarn include a binding synthetic resin yarn such as a polyamide resin yarn or a polyester resin yarn, and a stitch yarn such as a glass fiber yarn.

  Moreover, as a matrix resin of the said fiber reinforced synthetic resin body, either a thermoplastic resin or a thermosetting resin can be used, and a thermosetting resin is used preferably.

  The thermosetting resin impregnated into the reinforcing fiber is not particularly limited. For example, epoxy resin, unsaturated polyester resin, phenol resin, melamine resin, polyurethane resin, silicone resin, maleimide resin, vinyl ester resin, cyanate ester resin Etc. Examples of the thermosetting resin include a resin obtained by prepolymerizing a maleimide resin and a cyanate ester resin. The thermosetting resin is preferably an epoxy resin or a vinyl ester resin because it is excellent in heat resistance, impact absorption or chemical resistance. The thermosetting resin may contain additives such as a curing agent and a curing accelerator. In addition, as a thermosetting resin, 1 type may be used independently or 2 or more types may be used together.

The thermoplastic resin impregnated into the reinforcing fiber is not particularly limited, and examples thereof include olefin resins, polyester resins, thermoplastic epoxy resins, amide resins, thermoplastic polyurethane resins, sulfide resins, and acrylic resins. As a thermoplastic resin, since it is excellent in adhesiveness with a foam sheet laminated body or binding property between reinforcing fibers constituting the fiber reinforced synthetic resin body, a polyester resin or a thermoplastic epoxy resin is used. preferable. In addition, as a thermoplastic resin, 1 type may be used independently or 2 or more types may be used together.
The thermoplastic epoxy resin may be a homopolymer or copolymer of epoxy compounds having a linear structure, or a copolymer of an epoxy compound and a monomer that can be polymerized with the epoxy compound. And a copolymer having a linear structure. Specifically, as the thermoplastic epoxy resin, for example, bisphenol A type epoxy resin, bisphenol fluorene type epoxy resin, cresol novolac type epoxy resin, phenol novolac type epoxy resin, cyclic aliphatic type epoxy resin, long chain aliphatic type An epoxy resin, a glycidyl ester type epoxy resin, a glycidylamine type epoxy resin, and the like can be given. As the thermoplastic epoxy resin, bisphenol A type epoxy resin and bisphenol fluorene type epoxy resin are preferable. In addition, as a thermoplastic epoxy resin, 1 type may be used independently or 2 or more types may be used together.
Examples of the thermoplastic polyurethane resin include a polymer having a linear structure obtained by polymerizing diol and diisocyanate. Examples of the diol include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, and the like. As a diol, 1 type may be used independently or 2 or more types may be used together. Examples of the diisocyanate include aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate. As diisocyanate, 1 type may be used independently or 2 or more types may be used together. In addition, as a thermoplastic polyurethane resin, 1 type may be used independently or 2 or more types may be used together.

  The content of the matrix resin in the fiber-reinforced synthetic resin body is preferably 20 to 70% by mass, and more preferably 30 to 60% by mass. If the content of the matrix resin in the fiber reinforced synthetic resin body is too small, the binding property between the reinforced fibers and the adhesion between the fiber reinforced synthetic resin body and the foamed sheet laminate are insufficient, and the fiber reinforced synthetic resin body There is a possibility that the mechanical properties and the mechanical strength of the fiber-reinforced composite cannot be sufficiently improved. When there is too much content of matrix resin, there exists a possibility that the mechanical physical property of a fiber reinforced synthetic resin body may fall and the mechanical strength of a fiber reinforced composite body cannot fully be improved.

Basis weight of the fiber reinforced synthetic resin material is preferably ^{50~4000g / m 2, 100~1000g / m} 2 is more preferable. A fiber-reinforced synthetic resin body having a basis weight within the above range is excellent in mechanical properties despite being lightweight.
The thickness of the fiber reinforced synthetic resin body is preferably 20 to 2000 μm, and more preferably 50 to 1000 μm.

  In addition, although the foam sheet laminated body of this embodiment, the fiber reinforced composite, and the manufacturing method of a foam sheet laminated body had the said advantage by the said structure, the foam sheet laminated body of this invention, fiber The manufacturing method of the reinforced composite and the foamed sheet laminate is not limited to the above-described configuration, and the design can be appropriately changed.

  Next, the present invention will be described more specifically with reference to test examples.

  First, the measuring method of the physical-property value of the foam sheet of a test example, a foam sheet laminated body, and a fiber reinforced composite is demonstrated. Note that the measurement method described above is omitted below.

<Open cell ratio>
The open cell ratio was measured by a 1-1 / 2-1 atmospheric pressure method in accordance with ASTM D-2856-87.

<Compressive strength>
The compression characteristics of the foam sheet laminate were evaluated by “ratio 25% compressive stress” obtained by dividing “25% deformation compressive stress” by “apparent density of foam sheet laminate”.
The 25% deformation compressive stress of the foamed sheet laminate was measured by the method described in JIS K7220: 2006 “Hard foamed plastics—How to obtain compression characteristics”.
That is, the size of the test piece was 50 mm long × 50 mm wide × thickness (mm) of the foamed sheet laminate. And using Tensilon universal testing machine UCT-10T (manufactured by Orientec Co., Ltd.), universal testing machine data processing (manufactured by UTPS-237 Softbrain Co., Ltd.), the compression rate is the thickness of the foam sheet laminate per minute. The 25% deformation compressive stress of this test piece was determined as 10% thickness (mm). The number of test pieces shall be a minimum of 5, and after placing the test pieces in an environment of temperature 23 ± 2 ° C. and humidity 50 ± 5% for 16 hours or more, in an environment of temperature 23 ± 2 ° C. and humidity 50 ± 5% The 25% deformation compressive stress of the test piece was determined.
The 25% deformation compressive stress was calculated by the following equation.
(25% deformation compressive stress)
σ ₂₅ = F ₂₅ / A ₀
σ ₂₅ : 25% deformation compressive stress (MPa)
F ₂₅ : Force at the time of 25% deformation (N)
A ₀ : Initial cross-sectional area of the test piece (mm ² )
The ratio 25% deformation compressive stress was calculated by the following equation.
(Ratio 25% deformation compressive stress)
C ₂₅ = σ ₂₅ / ρ
C ₂₅ : ratio 25% deformation compressive stress (MPa / (g / cm ³ ))
σ ₂₅ : 25% deformation compressive stress (MPa)
ρ: Apparent density of test specimen (g / cm ³ )
And it evaluated on the following references | standards.
○: 6.5 MPa / (g / cm ³ ) or more ×: less than 6.5 MPa / (g / cm ³ )

<Bending strength>
Evaluation of the bending property of the foam sheet laminate was evaluated by “specific bending maximum point stress” obtained by dividing “maximum bending point stress” by “apparent density of foam sheet laminate”.
The bending maximum point stress of the foamed sheet laminate was measured by the method described in JIS K7221-1: 2006 “Rigid foamed plastic—Bending test—Part 1: Determination of flexural properties”.
That is, the size of the test piece was 25 mm wide × 120 mm long × thickness (mm) of the foamed sheet laminate. And using Tensilon universal testing machine UCT-10T (manufactured by Orientec Co., Ltd.), universal testing machine data processing (manufactured by UTPS-237 Soft Brain Co., Ltd.), the test speed is 10 mm / min, and the pressure wedge is 5R. The maximum bending stress of the test piece was obtained by setting the support base to 5R and the distance between supporting points to 100 mm. The number of test pieces is 5, and after placing the test pieces in an environment of temperature 23 ± 2 ° C. and humidity 50 ± 5% for 16 hours or more, the test is performed in an environment of temperature 23 ± 2 ° C. and humidity 50 ± 5%. The bending maximum point stress of the piece was obtained.
The maximum bending point stress was calculated by the following formula.
(Maximum bending stress)
R = 1.5FR × L / bd ²
R: Maximum bending point stress (MPa)
FR: Maximum point load (N)
L: Distance between fulcrums (mm)
b: Width of test piece (mm)
d: Test piece thickness (mm)
The specific bending maximum point stress was calculated by the following equation.
(Specific bending maximum point stress)
FL = R / ρ
FL: specific bending maximum point stress (MPa / (g / cm ³ ))
R: Maximum bending point stress (MPa)
ρ: Apparent density of test specimen (g / cm ³ )
And it evaluated on the following references | standards.
○: 20 MPa / (g / cm ³ ) or more Δ: 15 MPa / (g / cm ³ ) or more and less than 20 MPa / (g / cm ³ ) ×: less than 15 MPa / (g / cm ³ )

<Specific absorption energy>
The specific absorption energy of the fiber reinforced composite provided with the foamed sheet laminate as a core material was measured by the method described in JIS K7222-1: 2006 “Hard foamed plastic—bending test—Part 1: Determination of flexural properties”.
That is, the test piece size was 25 mm wide × 150 mm long × thickness (mm) of the fiber reinforced composite. And using Tensilon universal testing machine UCT-10T (manufactured by Orientec Co., Ltd.), universal testing machine data processing (manufactured by UTPS-237 Softbrain Co., Ltd.), the test speed is 10 mm / min, and the pressure wedge is 10R. The specific absorption energy of the test piece was determined by setting the support base to 10R and the distance between fulcrums to 100 mm. The number of test pieces is 5, and after placing the test pieces in an environment of temperature 23 ± 2 ° C. and humidity 50 ± 5% for 16 hours or more, the test is performed in an environment of temperature 23 ± 2 ° C. and humidity 50 ± 5%. The absorbed energy of the piece was determined.
The specific absorption energy was obtained by dividing the absorption energy by the apparent density of the fiber-reinforced composite, using the integral value of the load-displacement graph from the start of the test to the displacement indicating the maximum point load as the absorption energy.
The specific absorption energy was calculated by the following formula.
E _C = E / ρ × 10 ³
E _C : specific absorption energy (mJ / (g / cm ³ ))
E: Absorbed energy (J)
ρ: Apparent density of test specimen (g / cm ³ )

(Test Example 1)
Polyethylene terephthalate as a thermoplastic polyester resin (The Far East Industry, trade name “CH611”, melting point: 251 ° C., glass transition temperature: 78.1 ° C., crystallization temperature: 132 ° C., IV value 1.04) 96.4 parts by mass, 3.6 parts by mass of a masterbatch (polyethylene terephthalate content: 60% by mass, talc content: 40% by mass) containing polyethylene terephthalate containing talc as a bubble regulator and pyromellitic anhydride 0.20 mass part was prepared as a resin raw material for forming a foam sheet.

The melting point and crystallization temperature of polyethylene terephthalate were determined as follows.
That is, the DSC curve was obtained in the same manner as the DSC curve used for obtaining the amount of crystallization heat, the melting peak temperature obtained from the DSC curve was taken as the melting point, and the crystallization peak temperature obtained from the DSC curve was taken as the crystallization temperature.

The glass transition temperature described above was determined as follows.
That is, it was measured by the method described in JIS K7121: 1987 “Method for measuring plastic transition temperature”. However, the sampling method and temperature conditions were as follows. Using a differential scanning calorimeter device DSC 6220 (made by SII Nano Technology Co., Ltd.), about 6 mg of a sample is filled at the bottom of an aluminum measurement container so that there is no gap, and the sample is 10 ° C. The temperature was raised from 30 ° C. to 290 ° C. at a heating rate of min, quickly taken out after holding for 10 minutes, allowed to cool in an environment of 25 ± 10 ° C., and then cooled at 30 ° C. at a heating rate of 10 ° C./min. From the DSC curve obtained when the temperature was raised to 290 ° C., the midpoint glass transition temperature was calculated. At this time, alumina was used as a reference material. The midpoint glass transition temperature was determined from the standard (9.3 “How to determine the glass transition temperature”).

A resin composition is obtained by supplying the resin raw material to a hopper of a single screw extruder having a screw diameter of 65 mmφ, heating and melting the resin raw material at a maximum temperature of 290 ° C. in the extruder, and melt-kneading the resin raw material. It was.
Thereafter, butane (isobutane: 35% by mass, normal butane: 65% by mass) as a blowing agent was injected in the middle of the extruder at a rate of 0.38 parts by mass with respect to 100 parts by mass of the resin raw material, A foamable resin composition was obtained by melt-kneading the composition and a foaming agent.

Then, at the tip of the extruder, after the molten foamable resin composition is cooled to 275 ° C., a circular die having an annular discharge port attached to the tip of the extruder (70 mm diameter of the discharge port, A cylindrical foam sheet was formed by extrusion from a slit width of 1.00 mm.
Next, the foamed sheet is taken up while the inner surface of the foamed sheet is slidably contacted with the outer peripheral surface of a cooling mandrel having a diameter of 210 mm arranged on the downstream side (forward in the extrusion direction) of the circular die. The foamed sheet is cooled with a mandrel from the inside of the foamed sheet, air is blown onto the foamed sheet from the outside of the foamed sheet to cool the foamed sheet, and the foaming is performed with a cutter provided on the downstream side of the cooling mandrel. The sheet was continuously cut in the direction of extrusion to develop a flat sheet to produce a long belt-shaped polyester resin foam sheet (hereinafter also simply referred to as “foam sheet”).

The produced foamed sheet has a thickness of 1.8 mm, an apparent density of 0.35 g / cm ³ , an open cell ratio of 6%, and a crystallization heat amount of the sheet surface portion of 23.0 mJ / mg. The average aspect ratio of the bubbles was 0.38.
In addition, the average value of the aspect ratio of the bubbles in the foam sheet was measured by changing the “stacking direction” to the “thickness direction” when obtaining the average value of the aspect ratio of the bubbles in the foam sheet laminate.
Further, the crystallinity of the sheet surface was measured in accordance with JIS K7122: 1987 described above by slicing the foam sheet from the surface in a thickness direction of 0.3 mm and parallel to the thickness direction.

In a heating press equipped with two hot plates (180 mm × 180 mm), two foam sheets (180 mm long × 180 mm wide × 1.8 mm thick) laminated between two hot plates heated to 145 ° C. (2 sheets) No. of total thickness: 3.6 mm).
And while the laminated foam sheet is heated at a temperature (145 ° C.) equal to or higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is the laminated foam. Laminated foam sheet so as to be 0.4 mm smaller than the total thickness of the sheets (so as to be smaller by 11% of the total thickness of the laminated foam sheets) (distance between hot plates: 3.2 mm) Was pressed with the hot plate.
Next, while the laminated foam sheet is heated at a temperature (145 ° C.) higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is changed from 3.2 mm to 7. The foamed sheet was expanded by gradually spreading to 0 mm over 1 minute.
Then, by heating the laminated foam sheet for another 14 minutes at a temperature (145 ° C.) higher than the crystallization temperature of the thermoplastic polyester resin by the heat of the hot plate, the foam sheet is subjected to thermocompression bonding for a total of 15 minutes. I let you.
Next, the hot plate was cooled to 60 ° C. by water-cooling the inside of the hot plate of the hot press machine, and then a foam sheet laminate was obtained.

The produced foamed sheet laminate had a thickness of 7.0 mm and an apparent density of 0.17 g / cm ³ .

<Production of fiber reinforced composite>
^Two fiber reinforced synthetic resin sheets (thickness 300 μm, basis weight: 200 g / m ² , trade name “Pyrofil Prepreg TR3523 381KMP” manufactured by Mitsubishi Rayon Co., Ltd.) as a fiber reinforced synthetic resin body were prepared. The fiber-reinforced synthetic resin sheet is a sheet in which 40% by mass of an uncured epoxy resin is impregnated in a reinforcing fiber base material made of a twill weave made of carbon fibers. The fiber reinforced synthetic resin sheet was formed into a planar square shape having a length of 180 mm × width of 180 mm.
Then, the two fiber-reinforced synthetic resin sheets were superposed so that the length directions of the warp yarns of the reinforcing fiber bases of the fiber-reinforced synthetic resin sheets adjacent to each other were orthogonal.

  Next, an aluminum plate is prepared, and a release agent (trade name “Chem Lease 2166” manufactured by Chem Lease Japan Co., Ltd.) is applied to the upper surface of the aluminum plate and left for one day, thereby releasing the mold on the upper surface of the aluminum plate. Was given. In addition, since the sealing material and back valve which are mentioned later are arrange | positioned in the outer periphery part of the aluminum plate upper surface, the mold release process was not performed.

  As shown in FIG. 1, an aluminum plate whose upper surface has been subjected to a release treatment is used as the pressing member 3a, and the two fiber-reinforced synthetic resin sheets 2 superimposed on the surface of the pressing member 3a which has been subjected to the release treatment. The foam sheet laminate 1 was placed on the fiber-reinforced synthetic resin sheet 2.

  Apart from the above-mentioned fiber reinforced synthetic resin sheet, two more fiber reinforced synthetic resin sheets identical to the above were prepared, and the two fiber reinforced synthetic resin sheets were superposed in the same manner as described above. These two superposed fiber reinforced synthetic resin sheets 2 were placed on the foam sheet laminate 1 to prepare a fiber reinforced laminate A.

  Next, a pair of rod-like and rectangular parallelepiped spacers 4a and 4b were placed on the outside of both ends in the width direction of the fiber reinforced laminate A on the surface of the pressing member 3a subjected to the mold release treatment. The spacers 4a and 4b were made of an aluminum plate and had a thickness of 8.0 mm. Further, the upper surface of the spacers 4a and 4b that comes into contact with a pressing member 3b, which will be described later, was subjected to a mold release process in advance. And the aluminum plate which gave the mold release process to the lower surface was prepared as the press member 3b, and the press member 3b was laminated | stacked on the fiber reinforced laminated body A and spacer 4a, 4b. At this time, the release treatment surface of the pressing member 3b was in contact with the fiber reinforced laminate A and the spacers 4a and 4b.

A release film 5 (trade name “WL5200B-P” manufactured by AIRTECH) having a through hole and a breather cloth 6 (trade name manufactured by AIRTECH) are provided on the pressing member 3b so as to cover the entire surface of the pressing member 3b. “AIRWEAVE N4”) was laminated in order.
The release film 5 is formed of a tetrafluoroethylene-ethylene copolymer film. The release film 5 is formed with a large number of through-holes that penetrate between both surfaces and allow the epoxy resin in the fiber-reinforced synthetic resin sheet 2 to pass therethrough.
The breather cloth 6 is formed from a non-woven fabric made of polyester resin fibers, and is configured to be impregnated with an epoxy resin.

Cover the breather cloth 6 with a bagging film 7 (product name “WL7400” manufactured by AIRTECH) and sealant tape (manufactured by AIRTECH) with the outer peripheral edge of the bagging film 7 and the pressing member 3a facing the bagging film 7 as the sealing material 8. The fiber reinforced laminate A was hermetically bonded using a product name “GS43MR”).
The bagging film 7 is made of a nylon film. A back valve 9 (trade name “VAC VALVE 402A” manufactured by AIRTECH) was disposed on a part of the bagging film 7 to produce a laminated structure.

  Next, the vacuum pump was connected to the vacuum line, the laminated structure was supplied into the autoclave, and the back valve 9 of the laminated structure was connected to the vacuum line. And the air in the space part B sealed with the bagging film 7 is discharged | emitted from the fiber reinforced laminated body A to the direction of the breather cloth 6 which coat | covered the side surface of this fiber reinforced laminated body A via spacer 4a, 4b. By doing so, the inside of the space B was depressurized to a vacuum degree of 0.10 MPa. In addition, the pressure reduction in the space part B was continuously performed after that.

  Thereafter, the pressure in the space B is continuously reduced to suck and remove the air present in the fiber reinforced synthetic resin sheet 2 while increasing the temperature inside the autoclave at a heating rate of 4 ° C./min. The temperature was raised to 90 ° C., and the fiber reinforced laminate A was heated at 90 ° C. for 90 minutes (preheating step). By this preheating step, the epoxy resin in the fiber reinforced synthetic resin sheet 2 is softened to deform the fiber reinforced synthetic resin sheet 2 along the surface of the foam sheet laminate 1 and the fiber reinforced synthesis of the foam sheet laminate 1. The thermoplastic polyester resin contained in the surface portion on the surface on which the resin sheet 2 is laminated was softened appropriately.

Next, the inside of the autoclave is pressurized to a gauge pressure of 0.3 MPa, a pressing force is applied to the fiber reinforced laminate A through the pressing members 3a and 3b, and the inside of the autoclave is set to 130 ° C. at a heating rate of 4 ° C./min. Then, the temperature was raised until the temperature was increased, and the fiber-reinforced laminate A was heated at 130 ° C. for 60 minutes (curing step). Through this curing step, the epoxy resin in the fiber reinforced synthetic resin sheet 2 was cured to obtain a fiber reinforced synthetic resin layer. Then, when the inside of the autoclave is cooled and the inside of the autoclave reaches 60 ° C., the pressure inside the autoclave is released and returned to the atmospheric pressure, the fiber reinforced laminate A is taken out, and the fiber reinforced laminate A is cooled to room temperature. did. This obtained the fiber reinforced composite in which the fiber reinforced synthetic resin layer 2 was formed on both surfaces of the foam sheet laminated body.
A part of the excess epoxy resin in the fiber reinforced synthetic resin sheets 2 and 2 is absorbed by the breather cloth 6 through the through-holes of the release film 5 due to the pressurization to the fiber reinforced laminate A, and the other one. The part was absorbed by the breather cloth 6 without passing through the through hole of the release film 5.

(Test Example 2)
A foamed sheet was obtained in the same manner as in Test Example 1.
Next, in a heating press machine equipped with two hot plates (180 mm × 180 mm), three foam sheets (180 mm long × 180 mm wide × 1.8 mm thick) laminated between two hot plates heated to 145 ° C. (Total thickness of three sheets: 5.4 mm) was sandwiched.
And while the laminated foam sheet is heated at a temperature (145 ° C.) equal to or higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is the laminated foam. Laminated foam sheet so as to be 0.6 mm smaller than the total thickness of the sheets (so as to be smaller by 11% of the total thickness of the laminated foam sheets) (distance between hot plates: 4.8 mm) Was pressed with the hot plate.
Next, while the laminated foam sheet is heated at a temperature (145 ° C.) equal to or higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is changed from 4.8 mm to 10.10. The foamed sheet was expanded by gradually spreading to 0 mm over 1 minute.
Then, by heating the laminated foam sheet for another 14 minutes at a temperature (145 ° C.) higher than the crystallization temperature of the thermoplastic polyester resin by the heat of the hot plate, the foam sheet is subjected to thermocompression bonding for a total of 15 minutes. I let you.
Next, the hot plate was cooled to 60 ° C. by water-cooling the inside of the hot plate of the hot press machine, and then a foam sheet laminate was obtained.
Further, a fiber-reinforced composite was obtained in the same manner as in Test Example 1 except that this foamed sheet laminate was used and a spacer having a height of 11.0 mm was used.

(Test Example 3)
A foamed sheet was obtained in the same manner as in Test Example 1.
Next, in a heating press equipped with two hot plates (180 mm × 180 mm), four foam sheets (vertical 180 mm × width 180 mm × thickness 1.8 mm) are laminated between two hot plates heated to 145 ° C. (Total thickness of 4 sheets: 7.2 mm) was sandwiched.
And while the laminated foam sheet is heated at a temperature (145 ° C.) equal to or higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is the laminated foam. Laminated foam sheet so as to be 0.8 mm smaller than the total thickness of the sheets (so as to be smaller by 11% of the total thickness of the laminated foam sheets) (distance between hot plates: 6.4 mm) Was pressed with the hot plate.
Next, while heating the laminated foam sheet at a temperature (145 ° C.) equal to or higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is changed from 6.4 mm to 14.4. The foamed sheet was expanded by gradually spreading to 0 mm over 1 minute.
Then, by heating the laminated foam sheet for another 14 minutes at a temperature (145 ° C.) higher than the crystallization temperature of the thermoplastic polyester resin by the heat of the hot plate, the foam sheet is subjected to thermocompression bonding for a total of 15 minutes. I let you.
Next, the hot plate was cooled to 60 ° C. by water-cooling the inside of the hot plate of the hot press machine, and then a foam sheet laminate was obtained.
Further, a fiber-reinforced composite was obtained in the same manner as in Test Example 1 except that this foamed sheet laminate was used and a spacer having a height of 15.0 mm was used.

(Test Example 4)
A foamed sheet was obtained in the same manner as in Test Example 1.
Next, in a heating press equipped with two hot plates (180 mm × 180 mm), two foam sheets (180 mm long × 180 mm wide × 1.8 mm thick) laminated between two hot plates heated to 145 ° C. (Total thickness of two sheets: 3.6 mm) was sandwiched.
And while the laminated foam sheet is heated at a temperature (145 ° C.) equal to or higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is the laminated foam. Laminated foam sheet so as to be 0.4 mm smaller than the total thickness of the sheets (so as to be smaller by 11% of the total thickness of the laminated foam sheets) (distance between hot plates: 3.2 mm) Was pressed with the hot plate.
Next, while the laminated foam sheet is heated at a temperature (145 ° C.) higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is changed from 3.2 mm to 9. The foamed sheet was expanded by gradually spreading to 5 mm over 1 minute.
Then, by heating the laminated foam sheet for another 14 minutes at a temperature (145 ° C.) higher than the crystallization temperature of the thermoplastic polyester resin by the heat of the hot plate, the foam sheet is subjected to thermocompression bonding for a total of 15 minutes. I let you.
Next, the hot plate was cooled to 60 ° C. by water-cooling the inside of the hot plate of the hot press machine, and then a foam sheet laminate was obtained.
Further, a fiber-reinforced composite was obtained in the same manner as in Test Example 1 except that this foamed sheet laminate was used and a spacer having a height of 10.5 mm was used.

(Test Example 5)
A foamed sheet was obtained in the same manner as in Test Example 1.
Next, in a heating press machine equipped with two hot plates (180 mm × 180 mm), a foam sheet (180 mm long × 180 mm wide × 1.8 mm thick), PET film (between 180 hot plates heated to 145 ° C.) A product made by Toray Co., Ltd., trade name “Lumirror U34 # 50”, vertical 180 mm × width 180 mm × thickness 50 μm) and foamed sheet (length 180 mm × width 180 mm × thickness 1.8 mm) were sandwiched in this order.
And while the laminated foam sheet is heated at a temperature (145 ° C.) equal to or higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is the laminated foam. 0.4 mm smaller than the total thickness of the sheet and the PET film (so as to be smaller by 11% of the total thickness of the laminated foam sheet and the PET film) (distance between the hot plates: 3.2 mm ), And the laminated foam sheet was pressurized with the hot plate.
Next, while the laminated foam sheet is heated at a temperature (145 ° C.) higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is changed from 3.2 mm to 7. The foamed sheet was expanded by gradually spreading to 0 mm over 1 minute.
Then, by heating the laminated foam sheet for another 14 minutes at a temperature (145 ° C.) higher than the crystallization temperature of the thermoplastic polyester resin by the heat of the hot plate, the foam sheet is subjected to thermocompression bonding for a total of 15 minutes. I let you.
Next, the hot plate was cooled to 60 ° C. by water-cooling the inside of the hot plate of the hot press machine, and then a foam sheet laminate was obtained.
Further, a fiber-reinforced composite was obtained in the same manner as in Test Example 1 except that this foamed sheet laminate was used and a spacer having a height of 7.0 mm was used.

(Test Example 6)
A foamed sheet was obtained in the same manner as in Test Example 1.
Next, in a heating press equipped with two hot plates (180 mm × 180 mm), two foam sheets (180 mm long × 180 mm wide × 1.8 mm thick) laminated between two hot plates heated to 145 ° C. (Total thickness of two sheets: 3.6 mm) was sandwiched.
And while the laminated foam sheet is heated at a temperature (145 ° C.) equal to or higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is the laminated foam. Laminated foam sheet so as to be 0.4 mm smaller than the total thickness of the sheets (so as to be smaller by 11% of the total thickness of the laminated foam sheets) (distance between hot plates: 3.2 mm) Was pressed with the hot plate.
Next, while the laminated foam sheet is heated at a temperature (145 ° C.) equal to or higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is changed from 3.2 mm to 4. The foamed sheet was expanded by gradually spreading to 0 mm over 1 minute.
Then, by heating the laminated foam sheet for another 14 minutes at a temperature (145 ° C.) higher than the crystallization temperature of the thermoplastic polyester resin by the heat of the hot plate, the foam sheet is subjected to thermocompression bonding for a total of 15 minutes. I let you.
Next, the hot plate was cooled to 60 ° C. by water-cooling the inside of the hot plate of the hot press machine, and then a foam sheet laminate was obtained.
Further, a fiber-reinforced composite was obtained in the same manner as in Test Example 1 except that this foamed sheet laminate was used and a spacer having a height of 5.0 mm was used.

(Test Example 7)
A foamed sheet was obtained in the same manner as in Test Example 1.
Next, in a heating press equipped with two hot plates (180 mm × 180 mm), two foam sheets (180 mm long × 180 mm wide × 1.8 mm thick) laminated between two hot plates heated to 145 ° C. (Total thickness of two sheets: 3.6 mm) was sandwiched.
And while the laminated foam sheet is heated at a temperature (145 ° C.) equal to or higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is the laminated foam. Laminated foam sheet so as to be 0.4 mm smaller than the total thickness of the sheets (so as to be smaller by 11% of the total thickness of the laminated foam sheets) (distance between hot plates: 3.2 mm) Was pressed with the hot plate.
Next, while the laminated foam sheet is heated at a temperature (145 ° C.) equal to or higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is changed from 3.2 mm to 12. The foamed sheet was expanded by gradually spreading to 0 mm over 1 minute.
Then, by heating the laminated foam sheet for another 14 minutes at a temperature (145 ° C.) higher than the crystallization temperature of the thermoplastic polyester resin by the heat of the hot plate, the foam sheet is subjected to thermocompression bonding for a total of 15 minutes. I let you.
Next, the hot plate was cooled to 60 ° C. by water-cooling the inside of the hot plate of the hot press machine, and then a foam sheet laminate was obtained.
Further, a fiber-reinforced composite was obtained in the same manner as in Test Example 1 except that this foamed sheet laminate was used and a spacer having a height of 13.0 mm was used.

(Test Example 8)
A foamed sheet was obtained in the same manner as in Test Example 1.
Next, the two foam sheets (length 180 mm × width 180 mm × thickness 1.8 mm) were bonded using an adhesive (trade name “Araldite 2011” manufactured by HUNTSMAN), and the bonded foam sheet was 23 ° C. The foamed sheet laminate was prepared by placing it for 1 week in the above environment.
Further, a fiber-reinforced composite was obtained in the same manner as in Test Example 1 except that this foamed sheet laminate was used and a spacer having a height of 4.7 mm was used.

(Test Example 9)
A foamed sheet was obtained in the same manner as in Test Example 1.
Next, in a heating press equipped with two hot plates (180 mm × 180 mm), two foam sheets (180 mm long × 180 mm wide × 1.8 mm thick) laminated between two hot plates heated to 145 ° C. (Total thickness of two sheets: 3.6 mm) was sandwiched.
And while the laminated foam sheet is heated at a temperature (145 ° C.) equal to or higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is the laminated foam. Laminated foam sheet so as to be 0.4 mm smaller than the total thickness of the sheets (so as to be smaller by 11% of the total thickness of the laminated foam sheets) (distance between hot plates: 3.2 mm) Was pressed with the hot plate.
Next, while the laminated foam sheet is heated at a temperature (145 ° C.) higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is changed from 3.2 mm to 7. The foam sheet was expanded gradually over 3 minutes up to 0 mm, but foaming stopped at a thickness of 4.2 mm while expanding the distance between the hot plates, so the distance between the hot plates was 4.2 mm, The foam sheet was sandwiched between the hot plates without any gaps.
And by heating the laminated foam sheet for another 12 minutes at a temperature (145 ° C.) higher than the crystallization temperature of the thermoplastic polyester resin by the heat of the hot plate, the foam sheet is thermocompression bonded for a total of 15 minutes. I let you.
Next, the hot plate was cooled to 60 ° C. by water-cooling the inside of the hot plate of the hot press machine, and then a foam sheet laminate was obtained.
Further, a fiber-reinforced composite was obtained in the same manner as in Test Example 1 except that this foamed sheet laminate was used and a spacer having a height of 5.2 mm was used.

(Test Example 10)
A foamed sheet was obtained in the same manner as in Test Example 1.
Next, in a heating press equipped with two hot plates (180 mm × 180 mm), two foam sheets (180 mm long × 180 mm wide × 1.8 mm thick) laminated between two hot plates heated to 100 ° C. (Total thickness of two sheets: 3.6 mm) was sandwiched.
And while heating the laminated foam sheet at a temperature (100 ° C.) equal to or higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is the laminated foam. Laminated foam sheet so as to be 0.4 mm smaller than the total thickness of the sheets (so as to be smaller by 11% of the total thickness of the laminated foam sheets) (distance between hot plates: 3.2 mm) Was pressed with the hot plate.
Next, while the laminated foam sheet is heated at a temperature (100 ° C.) equal to or higher than the glass transition temperature of the thermoplastic polyester resin by the heat of the hot plate, the distance between the hot plates is changed from 3.2 mm to 7. While the foam sheet was expanded by gradually spreading to 0 mm over 1 minute, foaming stopped at a thickness of 5.3 mm while the distance between the hot plates was increased, so the distance between the hot plates was set to 5.3 mm. The foam sheet was sandwiched between the plates without any gaps.
The laminated foam sheet is further heated for 14 minutes at a temperature (100 ° C.) below the crystallization temperature of the thermoplastic polyester resin by the heat of the hot plate, so that the foam sheet is thermocompression bonded for a total of 15 minutes. I let you.
Next, the hot plate was cooled to 60 ° C. by water-cooling the inside of the hot plate of the hot press machine, and then a foam sheet laminate was obtained.
Further, a fiber-reinforced composite was obtained in the same manner as in Test Example 1 except that this foamed sheet laminate was used and a spacer having a height of 6.3 mm was used.

  The results are shown in Table 1.

  1: foam sheet laminate, 2: fiber reinforced synthetic resin sheet, 3a: pressing member, 3b: pressing member, 4a: spacer, 4b: spacer, 5: release film, 6: breather cloth, 7: bagging film, 8: Sealing material, 9: back valve, A: fiber reinforced laminate, B: space

Claims (10)

A plurality of foam sheets formed of thermoplastic polyester resin are laminated and integrated,
A plurality of foam layers formed of the foam sheet are provided,
The foam sheet laminated body whose average value of the aspect-ratio of the bubble shown to following formula (1) is 0.6-1.2.
Air bubble aspect ratio = bubble diameter in a direction perpendicular to the laminate surface of the foam sheet / bubble diameter in a direction parallel to the laminate surface of the foam sheet (1) Further comprising a non-foamed layer;
The foamed sheet laminate according to claim 1, wherein a ratio of the total thickness of the foamed layer to the total thickness of the non-foamed layer is 30 to 110. The plurality of foam layers are provided with a minimum density region having the smallest apparent density at the center in the thickness direction of each layer,
The foamed sheet laminate according to claim 1 or 2, wherein an average value of the aspect ratio of the bubbles in a region having the smallest apparent density among the plurality of the minimum density regions is 1.4 or more.   The foam sheet laminate according to claim 3, wherein an average value of the aspect ratios of the bubbles in the minimum density region is 1.3 or more in all the foam layers. The plurality of foam layers are provided with a minimum density region having the smallest apparent density at the center in the thickness direction of each layer,
The outermost surface is provided with a heat-melt layer formed by thermally melting one surface side of one of the plurality of foam sheets.
2. The apparent density of the surface layer portion including the thermal melt layer provided on the outermost surface is 1.3 times or more than the apparent density of the region having the smallest apparent density among the plurality of the minimum density regions. The foamed sheet laminated body of any one of -4. The outermost surface is provided with a heat-melt layer formed by thermally melting one surface side of one of the plurality of foam sheets.
The foamed sheet laminate according to any one of claims 1 to 5, wherein a crystallization heat amount of a surface layer portion including the hot melt layer provided on the outermost surface is 5.0 mJ / mg or less.   The foamed sheet laminate according to any one of claims 1 to 6, which is used as the core material of a fiber-reinforced composite comprising a core material and a fiber-reinforced synthetic resin body laminated on the surface of the core material. A foam sheet laminate as a core material, and a fiber-reinforced synthetic resin body laminated on the surface of the core material,
A fiber-reinforced composite in which the foamed sheet laminate according to claim 7 is used as the core material. A method for producing a foam sheet laminate, comprising integrating a plurality of foam sheets,
A first step of heating a laminated body formed by laminating a plurality of the foamed sheets formed of a thermoplastic polyester-based resin while regulating the laminated body to a thickness equal to or less than a natural state of the laminated body;
After the first step, while heating the laminate, a second step of increasing the thickness of the laminate and increasing the thickness of each of the foam sheets from the thickness before the first step, A method for producing a foam sheet laminate.   Before the first step, a thermoplastic polyester resin and a foaming agent are melt-kneaded and extruded and foamed to obtain at least one of the plurality of foamed sheets in the first step. The manufacturing method of the foam sheet laminated body of Claim 9 further equipped with a process.

Images